The external diameter of both MAF sensors are the same. 90mm
The internal diameters is where the difference is.
The stock MAF shrinks to its smallest diameter of 74mm. Area = 4300mm2
The new MAF has a continuous diameter of 85mm. Area = 5674mm2
The stock MAF's guide vane is 74mm x 11mm thick reducing the MAF area by 814mm2
The new MAF's sensing element tower is 17mm x 47mm PLUS 17mm + 22mm. Reducing the MAF area by 1173mm
The stock MAF's flowable surface area = 3486mm2
The new MAF's flowable surface area = 4501mm2
Nearly a 30% larger opening in the new MAF.
And if you really care... the new MAF is significantly lighter in weight as well.
Stock VX LS1 MAF (left) vs NEW DELPHI AF10056 MAF (right)
Area Differences
The adapter plug that comes with the new MAF
New DELPHI AF10056 installed with MAF Pipe and 2 Hole Monaro CAI